Study And Realization Of The Hybrid Spread Spectrum Transmitter Based On Software Radio

In order to meet the characteristics of modern warfare, the single electronic warfare technology for the military purposes is gradually developing to the integrated combat, which demands the combat system to further enhance the anti-jamming capability. Spread spectrum communication technology is an important anti-jamming communications technology in the field of the military communications. Through theoretical analysis and research about the spread spectrum communication technology, we designs a scheme of the transmitter that uses direct sequence/ frequency hopping (DS/FH) mixed mode based on software radio. The DS technology can improve the system bandwidth, and frequency hopping is essentially broadband transmission in this program, so the mixed-mode can gain wider bandwidths, which can achieve a lower noise ratio transmission, to ensure a better anti-interference about signal transmission. The entire transmitter system mainly consists of baseband subsystem,RF subsystem and frequency synthesis subsystem, The paper puts research emphasis on structure and implementation of hard platform based on software radio.The base-band platform architecture uses FPGA+ARM. The IF and RF parts use the integrated chip with high-performance of some companies. The base-band processor platform includes the base-band control section and the base-band data section. The base-band control section uses the LPC2103 for the controller. Through the module of asynchronous communication with the host computer modules for exchanging data, accessing to control commands and transmitting data. The base-band data section uses the Verilog hardware description language for FPGA programming. The functions of the IF part is realized by using the special digital-analog converter chip. The main functions of the RF part are completed with integrated chip, the frequencies moved from baseband to RF is completed by direct quadrature, the amplifier increases signal amplitude, the power of signal is amplified by power amplifier tube. Frequency synthesis subsystem uses DDS+PLL loop outside the mixing program to implement frequency hopping. We use Cadence software to complete transmitter's schematic design and PCB drawing, and analyze the signal integrity, finally, transmitter system is simulated and tested, The results verify the feasibility of the scheme.